Recently, dominant mutations in T-cell restricted intracellular antigen 1 (TIA1), which is an RNA-binding protein involved in SMN2 exon 7 splicing (Singh et al., 2011), were shown to play a causative role in ALS (Mackenzie et al., 2017), while TIA1 knockout modifies phenotypes of mild male SMA mice (Howell et al., 2017). Here, TIA1 is linked to proximal spinal muscular atrophy.